In a medium pot over medium-low heat, combine chopped rhubarb, granulated sugar, and orange juice. Cook the mixture covered for about 5 minutes, then uncover and continue to simmer for another 10-15 minutes, stirring occasionally, until the rhubarb breaks down and thickens. Remove from heat and allow the compote to cool completely.

In a separate pot, whisk together the corn starch and 100g of sugar. Gradually add the whole milk while continuously whisking to avoid lumps. Mix in the egg yolks, fine sea salt, vanilla bean paste, and optional ground cardamom. Cook over medium-low heat, stirring frequently until it thickens and gently bubbles, about 10 minutes. Remove from heat, stir in the salted butter until melted, and chill.

Using a stand mixer or hand mixer, whip the heavy cream with the remaining sugar until medium-stiff peaks form, about 3-5 minutes. Fold a quarter of the whipped cream into the chilled custard until fully incorporated. Carefully fold in the remaining whipped cream until smooth.

In a clear glass bowl or trifle dish, layer Nilla wafers, custard, rhubarb compote, and fresh raspberries. Repeat the layers until the dish is filled, finishing with custard cream on top.

Cover the assembled trifle with plastic wrap and refrigerate for at least 12 hours. When ready to serve, garnish with additional fresh raspberries and scoop out portions.